Hi Blaz,
I'm not sure exactly what could be causing the problem. Have you tried any of the tips in the tech forum?
Try deleting the cache files (simCompositorCache.package, scriptCache.package, compositorCache.package, CasPartCache.package)
Also delete everything except Ccmerged.package file in your DCBackup folder.
-- Documents > Electronic Arts > The Sims 3 > DCBackup
If the above steps don't help try a factory reset - Rename your current Sims 3 folder to something like Sims 3 Current. Click the Sims 3 icon to create a new Sims 3 folder. Then copy your game saves, files and such over to the new game to see if that helps.
If you need to know what to save/backup. Have a look at this thread.
Re: Saving folders/files to use on a different computer or to use as backup
http://www.carls-sims-3-guide.com/forum/index.php/topic,16414.msg313134.html#msg313134If you find that none of the above help, please post back so we maybe able to help further.
MrsFlynn